Cell division is the process by which a parent cell divides into two daughter cells. It occurs through two distinct processes, mitosis, and meiosis, each having its role in the life cycles of organisms. Mitosis is the division of a cell that produces two identical daughter cells, essential for growth and tissue maintenance. Meiosis on the other hand is a two-step division that takes place in the reproductive cells and produces gametes with half the number of chromosomes for sexual reproduction.

Phases of mitosis include Prophase, Metaphase, Anaphase, and Telophase. Mitosis ensures genetic continuity in somatic cells and meiosis introduces genetic diversity in offspring through the combination of parental genetic material.

In this article on Biology, we will learn about the Process of Cell Division, Types of Cell Division – Miin mitosisosis and Meiosis, their phases, Binary fission, Difference between Mitosis and Meiosis, etc.

What is Cell Division?

Cell division is a fundamental process that is important for the growth and development of living organisms. Cell division takes place through two processes: Mitosis and Meiosis.

Mitosis cell division involves the duplication of the genetic material and the segregation of the cell into two identical daughter cells. This process is essential for tissue repair, growth, and asexual reproduction in organisms.

On the other hand, meiosis is a specialized form of cell division that occurs in sexually reproducing organisms. Unlike mitosis, meiosis results in the formation of gametes (sperm and egg cells) with half the number of chromosomes. It ensures genetic diversity in offspring. Both mitosis and meiosis play important roles in the life cycles of organisms and contribute to the complexity and diversity of life on Earth.

Cell Division Diagram

The diagram below shows different phases of cell division.

Cell Division Cycle

The cell division cycle, also known as the cell cycle, is a series of events that take place in a cell leading to the division of its genome, synthesis of other cell components and ultimately dividing to produce two daughter cells. It consists of several phases, each with specific activities and checkpoints to ensure proper cell division.

The cell cycle is crucial for growth, development, tissue repair, and maintaining the overall integrity of multicellular organisms.

Types of Cell Division

Cell Division is broadly classified into 2 subtypes: Mitosis and Meiosis.

• Mitosis or Equational Division – daughter cells formed are exact replicas of parent cell.
• Meiosis or Reductional Division – daughter cell contain half the number of chromosome as present in parent cell.

Phases of the Cell Cycle

The cell cycle is comprises of two phases –

1. Interphase – It is the longest phase in the cell cycle representing growth period between two successive cell division.
2. Mitosis Phase or M-Phase – Represents phase where actual cell division occurs. It includes steps of karyokinesis and cytokinesis.

Mitosis Diagram

The various mitosis phases are shown below.

1. Interphase

Interphase is called the “resting phase” of cell cycle but studies show active synthesis of RNA, protein, and genetic material occurring during this phase.

The interphase further comprises into following phases:

1. G1 Phase (Gap 1): Cells mainly grow during this phase but does not undergo DNA replication. It performs normal functions.
2. S phase (Synthesis): DNA synthesis occurs, resulting in the replication of the genetic material.
3. G2 phase (Gap 2): The cell continues to grow, synthesizing proteins and preparing for mitosis or meiosis.
4. Quiescent Stage (G0): Some cells like nerve cells do not undergo cell division so they exits the G1 phase. They remain in G0 stage that is an inactive stage.

2. M Phase (Mitosis Phase)

Mitosis can be defined as the process where the chromosomes divides longitudinally into two halves and migrate to the opposite poles. They organize into two daughter nuclei which are identical to the parent cell.

This phase is further divided into following four stages –

• Prophase
• Metaphase
• Anaphase
• Telophase

Let’s go through each one of them in detail.

Prophase

• It is divided into two stages early and late prophase. In the early prophase, chromosomes condense and become visible. Nuclear envelope starts to break down and spindle fibers begin to form.
• In the late prophase, nuclear envelope fully disintegrates and spindle fibers extend across the cell, connecting to chromosomes.

Metaphase

• It starts when the mitotic spindle organizes all chromosomes and lines them up in the middle of the cell to divide, at the metaphase plate.
• The chromosomes now consist of two sister chromatids joined together by centromere.
• At this stage of metaphase, the two kinetochores of each chromosome attaches to microtubules from opposite spindle poles.

Anaphase

• In this stage, the chromatids separate from each other and move toward the opposite poles of the cell. These chromatids will form the daughter chromosomes of future daughter nuclei.
• Splitting of centromeres separates the sister chromatids.
• Spindle fibers pull chromatids to opposite poles of the cell.

Telophase

• In this stage, the cell is almost divided and starts to re-establish its normal cellular structures as cytokinesis takes place.
• Chromatids reach opposite poles and de-condense into chromosomes.
• The mitotic spindle breaks down and two new nuclei are formed, one for each set of chromosomes.

Cytokinesis

Cytokinesis is the final stage of cell division where the cell’s cytoplasm divides. In this process –

• A cleavage furrow forms in animal cells or a cell plate in plant cells.
• The cell membrane pinches inward, separating the two daughter cells.
• Organelles and cytoplasm are distributed to ensure each daughter cell is functional.
• Finally, two genetically identical daughter cells with complete cellular components are formed.

Also Read: Difference Between Karyokinesis And Cytokinesis

Meiosis

Meiosis is a cell division that take place in reproductive cells to produce gametes: sperm and egg cells. Cell division by meiosis includes two cycle of divisions, Meiosis I and Meiosis II, each with specific functions. In Meiosis I, the chromosome number is halved as homologous chromosomes separate. Crossing over occurs during Meiosis I, where genetic material is exchanged between homologous chromosomes.

Meiosis II follows, where the haploid cells produced in meiosis I undergoes further division to form four haploid daughter cells. Genetic recombination that occur during meiosis results in offspring with a combination of genetic material from both parents. This process ensure genetic diversity.

Meiosis Diagram

Stages of Meiosis

There are basically 2 stages of Meiosis: Meiosis I and Meiosis II. These are explained below:

Meiosis I:

1. Prophase I: Chromosomes condense, and homologous chromosomes (one from each parent) pair up in a process called synapsis. Crossing-over occurs, where genetic material is exchanged between homologous chromosomes.
2. Metaphase I: Homologous chromosome pairs align at the cell’s equator, known as the metaphase plate.
3. Anaphase I: Homologous chromosomes separate and move to opposite poles of the cell.
4. Telophase I: Chromosomes reach the poles, and the cell undergoes cytokinesis, resulting in two daughter cells, each with half the original chromosome number.

Meiosis II:

1. Prophase II: Chromosomes condense again in the haploid cells.
2. Metaphase II: Chromosomes align at the metaphase plate in each haploid cell.
3. Anaphase II: Sister chromatids of each chromosome are pulled apart and move to opposite poles.
4. Telophase II: Chromatids reach the poles, and the cells undergo cytokinesis, producing four haploid daughter cells, each genetically distinct.

Tabular Difference Between Mitosis and Meiosis

The Difference Between Mitosis and Meiosis are as follows: